largefiles: don't hash all largefiles when initializing a lfdirstate The largefiles will be hashed on demand if necessary ... and sometimes it isn't necessary.

largefiles: use filechunkiter for iterating largefile when serving getlfile The default file iterator is line based and will give odd chunk sizes - often very short and relatively expensive.

largefiles: stat all largefiles in one batch before downloading This avoids a lot of expensive roundtrips to remote repositories ... but might be slightly slower for local operations. This will also change some aborts on missing files to warnings. That will in some situations make it possible to continue working on a repository with missing largefiles.